1. Field of the Invention
The present invention is broadly concerned with methods and apparatuses for applying a foamed product, comprising very small amounts of additive substances and requiring very small amounts of liquid carrier, to a large mass of materials such as animal feed. The product can be foamed by use of a foaming agent (either with or without subsequent agitation) or by agitating a suspension comprising the additive and liquid carrier without the addition of a foaming agent. Agitation can be carried out by any conventional mixing or vibrating mechanism or by injecting air under pressure into the suspension. Foaming of the suspension results in a product having increased surface area thus permitting an even, thorough distribution of the foamed additive onto the animal feed.
2. Description of the Prior Art
Animal feed additives, such as vitamins, innoculants, and nutritional supplements, are generally mixed with animal feed after the pellet is formed. Typically, a quantity of the additive material is measured by hand and added to a tank containing a specific, measured quantity of a liquid carrier such as oil or water. A stirrer is provided within the tank in an attempt to maintain the additive(s) in suspension, and the tank is then pressurized to direct the mixture through a spray nozzle and onto the feed pellets. This method has many drawbacks. An excess amount of the additive/liquid carrier suspension must be prepared in order to ensure the amount is sufficient to treat all of the feed. While this leads to wastage, the alternative is to make too little additive/liquid carrier suspension, thus requiring additional time and labor to prepare a new batch. Another drawback with this method is that the tank and mixing apparatus must be thoroughly cleaned after each use in order to prevent the growth of algae and other undesirable organisms.
Many of these problems were eliminated by the dosifying apparatus patented in U.S. Pat. No. 5,718,507 which provides a system for applying accurately metered, minute quantities of concentrated additives from bulk sources of supply to successive masses of material. While the system of the '507 is a vast improvement, it still requires the use of a large quantity of a liquid carrier (such as water) for the additives in order to ensure that all of the feed is covered with the additive. This results in wet feed which leads to mold growth on and spoilage of the feed. Furthermore, it is expensive and undesirable to use large quantities of the liquid carrier. This is especially true when water is the carrier, and the system is being used in an area where water is not plentiful. Finally, the spraying of the liquid carrier/additive suspension disclosed in the '507 patent results in splattering of the suspension, creating a wet, messy dispensing area and wasting valuable additives.